1. Field of the Invention
The present invention relates to an image processing apparatus.
2. Related Background Art
An apparatus of the type described above, e.g., a facsimile system performs communication of image data. A facsimile system has three modes: transmission, reception, and copying modes. In the transmission mode, an original is read and read image data is sent. In the reception mode, the image data sent from another system is recorded on a recording medium such as paper. In the copying mode, an original is read and is recorded directly.
In systems as described above, an image is generally read in the following manner. As the image is read and a memory for temporarily storing the read image data becomes full, the image signals are read out from the memory and recorded. When the memory thus becomes empty, image reading is resumed. This operation is repeated.
However, in such a system, the image reading operation is interrupted each time the memory is full. Therefore, the reproduced image becomes discontinuous and a poor image.
When an image is recorded, image signals are stored in a buffer memory and are then read out therefrom for recording. When all image signals stored in the buffer memory are read out and recorded, the recording operation is interrupted. The recording operation resumes when image signals are stored in the buffer memory. For this reason, there may occur an image displacement at seam of a recorded image. In particular, when the capacity of the buffer memory used is small, the image quality is significantly degraded.
If the capacity of the buffer memory corresponds to one page of originals, the above problem is solved. However, this results in a requirement of a large-capacity memory, resulting in an expensive system.
In image reading/recording, at least two drive motors are used in most image communication apparatuses. More specifically, a read motor is used for reading originals, and a record motor is used for recording images. In the copying mode, both the motors are driven.
However, with a recent trend for smaller and inexpensive image communication apparatuses such as facsimile systems, the use of two motors is disadvantageous and the use of a single motor has been studied.
FIG. 7 shows an example of the construction of a facsimile system using a single motor. Referring to FIG. 7, the system has a read roller 72 for conveying an original 71 in the transmission mode and a record roller 74 for conveying a recording medium 73 in the reception mode. In image communication (e.g., facsimile communication), the read roller 72 is driven in the transmission mode, the record roller 74 is driven in the reception mode, and both the rollers 72 and 74 are driven in the copying mode.
However, in the reception mode, the read roller 72 can also be driven in addition to the record roller 74. In this case, a single common reversible motor 75 is used. A rotating shaft (primary mover shaft) 76 of the motor 75 is rotated in the forward direction (X-direction) in the transmission mode, and in the reverse direction (Y-direction) in the reception or copying mode. One-way clutches 77 and 78 for transmitting motor rotation in only predetermined directions are mounted on the shaft 76. A one-way clutch 81 is mounted on a driven shaft 80 which is driven by the shaft 76 through a pair of gears (gear pair) 79.
Only when the motor rotating shaft 76 is rotated in the X-direction, does the one-way clutch 77 transmits the rotation to the read roller 72 through a belt 82. When the shaft 76 is rotated in the Y-direction, the clutch 77 does not transmit the rotation. Similarly, only when the motor rotating shaft 76 is rotated in the Y-direction, does the one-way clutch 78 transmits the rotation to the record roller 74 through a belt 84. When the shaft 76 is rotated in the X-direction, the clutch 77 does not transmit the rotation. Only when the driven shaft 80 is rotated in an X'-direction through the gear pair 79, does the one-way clutch 81 transmits the rotation. When the shaft 80 is rotated in the reverse direction, the clutch 81 does not transmit the rotation.
In the transmission mode, the motor 75 is rotated in the X-direction. Therefore, the rotation of the motor 75 is transmitted only by the clutch 77, and the remaining clutches 78 and 81 slip. In this case, rotational is transmitted only to the read roller 72 through the belt 82, and the original 71 is fed in the direction indicated by arrow A.
In the reception or copying mode, the motor 75 is rotated in the Y-direction. The one-way clutches 78 and 81 transmit the rotation but the clutch 77 does not. In this case, the rotation is transmitted to the read roller 72 through a belt 83 as in the transmission mode, and to the roller 74 through the belt 84. Both the rollers 72 and 74 are therefore rotated simultaneously.
In the system having the above configuration, transmission, reception and copying can all be performed with a single motor. However, in the reception or copying mode, rotation must be simultaneously transmitted to the rollers 72 and 74. For this reason, a motor having a higher torque than that when two motors are used is required. When such a high-torque motor is used, the manufacturing cost, motor size and heat generated are all increased, thus compromising compactness and low cost of the system.
In view of the above situation, an apparatus which requires only a single motor of a low torque has been desired.